The dumb move was to sign him to a two year extension before the season had even begun. You could see the decline coming and it got worse this season. Even if sticking with him, they could have easily got him for a lot less if they waited until the end of the season to offer an extension, especially since they refuse to renegotiate contacts. Bombers have a history of tying themselves to extensions for QBs on their way down.
They would have also had the time to see if Wilson or a prospect from another team may have been an option at the end of the season and could have begun a transition if that opportunity presented itself.